Boot certain Linux distributions from ISOs in ten steps:

1. Debian Live 10 amd64 gnome non-free
2. Debian Live 10 amd64 standard non-free
3. Fedora Silverblue x86_64 31 installation image
4. Lubuntu 18.04 desktop i386

The Debian distributions selected above include non-free firmware, for devices including WiFi adapters. Distribution 1 does not include a desktop environment.

For simplicity these instructions don't check any GnuPG signatures on checksums; checking signatures on checksums is a good practice and should be considered.

Alpine Linux does not appear to support booting ISO images directly; there is an open issue on the bug tracker.

The process below will:

• check a device for errors
• format the disk with a single "FAT32" partition in a GPT partition table
• download distribution 1 above
• install grub including settings to boot distribution 1

These steps have been tested from distribution 1 above.

1. Clear the kernel ring buffer with dmesg -c, insert the USB device, and clear the ring buffer again is order to identify the device. In the example below the device is /dev/sdb.

   $ sudo dmesg -c
   ✂
   [   XX.XXXXXX] sd X:0:0:0: [sdb] Attached SCSI removable disk
   

2. Check the device for errors:

   sudo badblocks -v -w /dev/sdb

   This is a slow process as the entire device will be written several times.
3. Partition the disk: GPT partition table (g), single new partition with default number, start and end (n), type of Microsoft Basic Data (t, 11, w):

   sudo fdisk /dev/sdb

4. Connect to the internet.
5. Install grub and mkfs.vfat:

   sudo apt update &&
   sudo apt install --yes curl dosfstools grub-efi-amd64-bin

6. Format and mount the disk:

   sudo mkfs.vfat -v -n distributio /dev/sdb1 &&
   sudo mount /dev/sdb1 /mnt &&
   cd /mnt

7. Install grub onto the device:

   sudo grub-install -v --target=x86_64-efi --efi-directory=. --boot-directory=.
   --removable --no-uefi-secure-boot

8. Download these files:

   curl -L https://github.com/maxwell-k/distributio/archive/master.tar.gz |
   sudo tar xz --strip-components=1

9. Download and check an ISO then generate grub configuration:

   sudo sh bin/prepare.sh debian-live-10.?.?-amd64-gnome+nonfree.sh

10. Reboot.

To test manually, the following should succeed:

rm *.sha256 *.iso
sh bin/prepare.sh debian-live-10.?.?-amd64-gnome+nonfree.sh
sh bin/prepare.sh debian-live-10.?.?-amd64-standard+nonfree.sh
sh bin/prepare.sh Fedora-Silverblue-ostree-x86_64-31-1.9.sh
sh bin/prepare.sh lubuntu-18.04-desktop-i386.sh

Booting into each distribution should also be tested.

• https://docs.pagure.org/docs-fedora/bootloading-with-grub2.html
• https://wiki.archlinux.org/index.php/Multiboot_USB_drive
• https://wiki.debian.org/Firmware
• https://www.gnu.org/software/grub/manual/grub/grub.html
• https://manpages.debian.org/buster/grub2-common/grub-install.8.en.html
• http://man7.org/linux/man-pages/man7/dracut.cmdline.7.html
• https://github.com/aguslr/multibootusb